The present invention relates to systems for monitoring the operation of a boom. In particular, the present invention relates to a system for monitoring operation of a boom in which loads or forces on the boom's components are sensed, information based upon the sensed loads or forces is stored, and an output is provided based upon the stored information which is indicative of potential causes and predicted timing of boom failure.
Boom systems frequently include a boom with one or more boom sections which are typically used to lift a load or reach to a particular distant location, a rotational actuator mechanism such as a rack and pinion mechanism for rotating the boom, and outriggers or extendable support legs for stabilizing the boom. Each boom section has a corresponding actuator assembly which supports the boom section as well as any load supported by that boom section. Typically, the actuator assemblies are hydraulic piston/cylinder assemblies. Forces generated by the actuator assemblies and by lifted loads or obstacles making contact with the boom act upon boom components during boom system operation. The maximum loads or forces that the actuator assemblies, boom sections and other boom system components are structurally designed to withstand are generally known by the boom manufacturer. This information may be translated to maximum loads or forces that each of the boom's structural or mechanical components can support or withstand without exceeding design limitations.
Boom systems are frequently subjected to work conditions in which loads supported by and forces experienced by the boom exceed design limitations. These excessive conditions can be caused for example by lifting excessive loads, by attempting to extend the boom while a section of the boom is pinned against a wall or other obstacle, by a foreign object such as a separate piece of machinery falling on a section of the boom, and by rotating the boom while a boom section or a distribution hose is tangled with an obstacle. Abuses such as these occur in construction applications on a daily basis. Frequently, the result is shortened boom life and/or the failure of one or more boom sections, actuator assemblies, outriggers or other components.
A very common problem experienced by boom manufacturers is that customers frequently deny that a failed boom was subjected to abusive conditions. In lawsuits in which someone was injured by a cracked boom or a boom which has tipped over, boom manufacturers frequently find it difficult to prove that the failure was caused by abuse, and not by a defect in the boom. Also, frequent abuse of booms makes it difficult for boom manufacturers to offer warranties to their customers. Fixing or replacing boom components which have failed as a result of being subjected to excessive loads, as opposed to being the result of manufacturing defects, is typically cost prohibitive.
Even if a boom is not subjected to loads which exceed design limitations, boom components may still experience fatigue failure because of the repetitious nature of boom movements under loaded conditions. Because fatigue failure is dependent upon the total number of cycles experienced by the boom components, and because the manufacturer has no way to determine how many cycles a particular user will put the boom through in a given period of time, predicting when boom components will experience fatigue failure is extremely difficult.